This invention relates to a high temperature superconducting rotor for a synchronous machine.
Typically, a superconducting winding of the rotor in a superconducting machine is cooled with a cryogenic refrigeration system. In the event of a refrigeration system failure, the superconducting winding will heat and eventually quench, leading to total machine failure.
A rotor having a thermal reserve arranged about a high temperature superconducting (HTS) winding is provided. In the event of a refrigeration system failure, the thermal reserve absorbs thermal energy from the HTS winding, thereby reducing the rate of increase of the temperature of the superconducting winding.
In accordance with one aspect of the invention, a high temperature superconducting rotor is provided including a high temperature superconducting field winding, a field winding support concentrically arranged about the high temperature superconducting field winding, and a thermal reserve concentrically arranged about the field winding support. The thermally reserve is coupled to the field winding to maintain a temperature differential between the thermal reserve and the field winding not greater than about 10 K.
Embodiments of this aspect of the invention may include one or more of the following features.
The thermal reserve includes a thermally conductive material. The material is electrically conductive, for example, aluminum or ATTA(copyright). The material includes segmentation normal to the rotor axis, along the rotor axis, or both. The material, for example, aluminum, is shrunk fit over the field winding support.
Alternatively, the thermal reserve includes a material that is electrically nonconductive, for example, a ceramic, including beryllium oxide or alumina.
The rotor includes a banding concentrically arranged about the thermal reserve. The banding includes an electrically conductive material, for example, steel, an electrically nonconductive material, for example, Kevlar or glass fiber, or both. The banding includes segmentation normal to the rotor axis.
The rotor includes an outer layer concentrically arranged about the thermal reserve. The outer layer includes a thermally nonconductive material. The outer layer includes either electrically conductive materials, electrically nonconductive materials, or both. Electrically conductive materials in the outer layer are configured to prevent the flow of eddy currents; for example, a layer of aluminum coated mylar is used. The aluminum coating includes segments. A banding is concentrically arranged about the outer layer.
In accordance with another aspect of the invention, a superconducting machine has a rotor. The rotor includes a high temperature superconducting field winding and a field winding support for securing the field winding. The support is electrically isolated from the field winding. An AC flux shield is concentrically arranged about the field winding. A thermal reserve is concentrically arranged about the AC flux shield and thermally coupled to the field winding to maintain a temperature differential between the thermal reserve and the field winding not greater than about 10 K. The machine further includes a stator concentrically arranged about the rotor.
In accordance with an embodiment of this aspect of the invention, a cryogenic refrigeration system is thermally coupled to the rotor.
In accordance with another aspect of the invention, a method is provided for limiting the rate of increase in the temperature of a superconducting winding. The method includes concentrically arranging a thermal reserve about and in thermal contact with the superconducting winding, and maintaining a temperature diferrential between the thermal reserve and the field winding no greater than about 10 K.
Embodiments of this aspect of the invention may include one or more of the following features.
The invention includes within the thermal reserve a thermally conducting material. Within the thermal reserve, an electrically nonconductive material is disposed between segments of an electrically conductive material. Within the thermal reserve, configuring the electrically nonconductive material to suppress eddy currents. The invention further includes concentrically arranging a thermally nonconductive material about the thermally conductive material.
According to another aspect of the invention, a high temperature superconducting rotor includes a high temperature superconducting field winding, a field winding support concentrically arranged about the high temperature superconductor field winding, and a thermal reserve concentrically arranged about the field winding support. The thermal reserve includes ATTA(copyright) which is thermally conductive and electrically nonconductive.